title: High serum interleukin-6 level is associated with increased risk of delirium in elderly patients after noncardiac surgery: a prospective cohort study.
abstract: BACKGROUND
  The relationship between inflammation and delirium remains to be determined. The purposes of this study were to investigate the association between serum interleukin-6 levels and the occurrence of delirium in elderly patients after major noncardiac surgery.
  
  
  METHODS
  A total of 338 elderly patients (60 years of age and over) undergoing major noncardiac surgery were enrolled. Blood samples were obtained before anesthesia and in the first postoperative morning and serum interleukin-6 concentrations were measured. Delirium was assessed twice daily by the confusion assessment method for the Intensive Care Unit during the first three postoperative days. Survival analyses were performed to assess the relationship between the serum IL-6 level and the occurrence of postoperative delirium.
  
  
  RESULTS
  Postoperative delirium occurred in 14.8% (50 of 338) of patients. High serum interleukin-6 levelsafter surgery were significantly associated with increased risk of the occurrence of postoperative delirium (hazard ratio 1.514, 95% confidence interval 1.155-1.985, P = 0.003). Other independent predictors of delirium included increasing age, poor preoperative New York Heart Association classification, low preoperative Mini-Mental State Examination score, and high total postoperative Visual Analogue Scale pain score. Patients who developed delirium had a prolonged hospital stay after surgery.
  
  
  CONCLUSIONS
  Delirium is a frequent complication in elderly patients after noncardiac surgery. High serum interleukin-6 level after surgery is associated with increased risk of the occurrence of postoperative delirium.
authors.affiliation: Department of Anesthesiology and Surgical Intensive Care, Peking University First Hospital, Beijing 100034, China.
authors.forename: Pei
authors.initials: P
authors.lastname: Liu
authors.forename: Ya-wei
authors.initials: YW
authors.lastname: Li
authors.forename: Xiao-shan
authors.initials: XS
authors.lastname: Wang
authors.forename: Xi
authors.initials: X
authors.lastname: Zou
authors.forename: Da-zhi
authors.initials: DZ
authors.lastname: Zhang
authors.forename: Dong-xin
authors.initials: DX
authors.lastname: Wang
authors.forename: Shi-zhong
authors.initials: SZ
authors.lastname: Li
mesh_terms: D000368:Aged; D015331:Cohort Studies; D003693:Delirium / Q000209:etiology* / Q000276:immunology; D005260:Female; D006801:Humans; D015850:Interleukin-6 / Q000097:blood*; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications / Q000097:blood / Q000209:etiology*; D011446:Prospective Studies; D012306:Risk
chemical_list: C508600:IL6 protein, human; D015850:Interleukin-6